FIG. 9 is a block diagram showing an example of a conventional configuration of an on-board power supply system. Such a configuration is well-known from, for example, JP 9-233694A.
A fuse box 70 includes fuses 71 to 74. Proximal ends of these fuses are each connected to a power supply line 61 at points inside the fuse box 70.
Distal ends of the fuses 71 to 74 are respectively connected to a general load 81, a general load 82, an important load 85, and a general load 86 at points outside the fuse box 70.
The power supply line 61, a starter 3 (denoted as “ST” in the figure), and an alternator 4 (denoted as “ALT” in the figure) are connected to a main battery 1 via individual fuses included in the fuse set 11.
The fuse set 11 is realized using, for example, a battery fuse terminal (hereinafter abbreviated to “BFT”).
The configuration shown in FIG. 9 lacks redundancy regarding the supply of power (hereinafter referred to as “power supply”). Specifically, if a voltage drop occurs due to a decrease in the current capacity of the main battery 1, for example, or if an open-circuit failure occurs due to the power supply line 61 and the fuse set 11 being disconnected from each other, for example, there is a problem in which all of the loads connected to the fuse box 70 are not supplied with power.
For example, when compared with the general load 86, the important load 85 has functional units that are desirable for vehicle security, such as actuators for steering and braking. It is desirable that power is supplied to the important load 85 even when power is not supplied to the general load 81, 82, or 86.
Therefore, it has been proposed to improve redundancy regarding power supply by providing a plurality of power supply paths to the important load 85. Such technology is well-known from JP 2015-83404A, for example.